1. Field of the Invention
The present invention relates to a side emitting lens, a backlight unit including the side emitting lens, and a liquid crystal display including the side emitting lens. More particularly, the present invention relates to a side emitting lens that may reduce optical loss and improve light emitting ratios, and a backlight unit and liquid crystal display including the side emitting lens.
2. Discussion of the Background
Light emitting diodes (LED), fluorescent lamps, metal halide lamps, and the like have been used as light sources for backlights of liquid crystal displays. Light emitting diodes have a long life span and do not require separate inverters. Further, light emitting diodes provide a thin and uniform backlight and have low power consumption. For these reasons, light emitting diodes tend to be widely used as a light source of a backlight for a liquid crystal display.
Direct-type backlights using light emitting diodes are classified as top emitting backlights and side emitting backlights on the basis of light emitting types thereof. Due to the optical efficiency of light emitting diodes, top emitting backlights are commonly used. However, top emitting backlights using light emitting diodes have lower light distribution and light uniformity than side emitting backlights.
Also, if the optical efficiency of the light emitting diode increases and exceeds the optical efficiency of a cold cathode fluorescent lamp, side emitting backlights, which have better light distribution and light uniformity than top emitting backlights, will become even more desirable.
When a general side emitting backlight employing light emitting diodes is used, primary optical loss occurs when light emitted from side surfaces of the lens is reflected by a bottom surface of the lens. Secondary optical loss is caused when light having a changed light path passes through a light guide plate. Then, since dot patterns printed on the light guide plate block the light emitted upward, tertiary optical loss may be caused.
Accordingly, there is a demand for a side emitting lens that can reduce optical loss and improve the light emitting ratios of the side surfaces and the lower surface of the lens, thereby improving the optical efficiency of a side emitting backlight employing light emitting diodes.